> On Aug. 13, 2015, 5:31 p.m., Alejandro Fernandez wrote:
> > ambari-server/src/main/resources/stacks/HDP/2.2/upgrades/upgrade-2.3.xml, 
> > line 580
> > <https://reviews.apache.org/r/37437/diff/1/?file=1039334#file1039334line580>
> >
> >     Di, can you explain this some more?
> >     This is performing an RU from HDP 2.2 -> 2.3, and that property exists 
> > in HDP 2.3, so due to config merging, it means that if the property does 
> > not exist or the user has not modified it, it will be set to  
> > *...HistoryServerLeveldbStateStoreService.
> >     Note: if the user does modify it, their value will be preserved.
> >     
> >     From your description, it sounds like the property does not work in HDP 
> > 2.2, so why should there be a PreCheck for it at all?
> 
> Di Li wrote:
>     hello Alejandro,
>     
>     AMBARI-12276 added "MapReduce2JobHistoryStatePreservingCheck" class, a RU 
> precheck class that checks whether "mapreduce.jobhistory.recovery.enable", 
> "mapreduce.jobhistory.recovery.store.class", and 
> "mapreduce.jobhistory.recovery.store.leveldb.path" are set in the 
> mapred-site.xml.
>     
>     In my tests, I updated an HDP 2.2 cluster to HDP 2.3, then I clicked 
> downgrade instead of Finalize. The downgrade kept the three properties in the 
> configuration for the MapRed2 history server. Because the HDP 2.2 version of 
> the MapRed history server does not have the class, it failed to start and 
> shown as stopped post downgrade.
>     
>     So my thinking was that I would modify the upgrade-2.3.xml to remove the 
> three mapred properties during the downgrade. If users want to perform 
> another round of rolling upgrade, they will need to manually add the three 
> properties back to the mapred-site.xml
> 
> Alejandro Fernandez wrote:
>     So on the brand new HDP 2.2 cluster, the 
> "mapreduce.jobhistory.recovery.store.class" property did not exist by 
> default, so you had to add it before starting RU to get the PreCheck to pass?

hello Alenjandro,

yes, in my test, I had to manually added the three mapred properties to the 
"Custom mapred-site" section before kicking off the rolling upgrade. Otherwise, 
RU precheck fails with err about the mapred props do not exist.

I am not sure if this should have been done differently as in using the 
upgrade-2.3.xml to insert the properties on the fly during the rolling upgrade.


- Di


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On Aug. 13, 2015, 1:13 p.m., Di Li wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/37437/
> -----------------------------------------------------------
> 
> (Updated Aug. 13, 2015, 1:13 p.m.)
> 
> 
> Review request for Ambari and Alejandro Fernandez.
> 
> 
> Bugs: AMBARI-12751
>     https://issues.apache.org/jira/browse/AMBARI-12751
> 
> 
> Repository: ambari
> 
> 
> Description
> -------
> 
> RU precheck requires "mapreduce.jobhistory.recovery.store.class" property to 
> be set in the mapred-site.xml with value 
> "org.apache.hadoop.mapreduce.v2.hs.HistoryServerLeveldbStateStoreService"
> 
> With this value set, the HDP 2.2 level MapRed history server can not start. 
> It shows an err about class 
> org.apache.hadoop.mapreduce.v2.hs.HistoryServerLeveldbStateStoreService does 
> not exist.
> 
> When downgrading, the mapred properties added to pass the RU precheck needs 
> to be removed.
> 
> 
> Diffs
> -----
> 
>   ambari-server/src/main/resources/stacks/HDP/2.2/upgrades/upgrade-2.3.xml 
> f6823c8 
> 
> Diff: https://reviews.apache.org/r/37437/diff/
> 
> 
> Testing
> -------
> 
> manually patch cluster to run rolling upgrade, after it passes the Core 
> Master step (which includes upgrading the MapRed2 History server), run 
> downgrade, verify the MapRed2 history server is still running once the 
> downgrade is done, the three mapred properties added to satisfy the ru 
> precheck are removed.
> 
> 
> Thanks,
> 
> Di Li
> 
>

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